Internal combustion engines are engines in which a combustible mixture, such as an air-fuel mixture, is ignited in a combustion chamber of the engine in order to apply force to a component of the engine. In a reciprocating piston internal combustion engine, such as an Otto cycle engine or a diesel engine, the combustion chamber is a cylinder that houses a reciprocating piston. Combustion of the fuel causes continued reciprocation of the piston, and the reciprocating motion of the piston is converted into a rotational output by a crankshaft that is coupled to the reciprocating piston by a connecting rod. Inefficiencies are associated with the reciprocating motion of the piston. For example, combustion occurs at or near top dead center, where the torque angle between the piston and the crankshaft is at or near zero.
Rotary internal combustion engines of many types have been proposed as alternatives to reciprocating piston internal combustion engines with varying degrees of success. Some rotary internal combustion engine designs place one or more pistons within a “cylinder” in the form of a torus. These engines are sometimes referred to as toroidal internal combustion engines. Some of these designs include one or more pistons that travel in a continuous circular motion without reciprocation, while turning an output shaft in unison with the motion of the piston. While this arrangement avoids some of the sources of inefficiencies experienced in reciprocating piston internal combustion engines, previously proposed designs have failed to achieve success.